Floating dry dock



Defio 1951 G. c. ENGSTRAND 2,576,928

FLOATING DRY DOCK Filed Nov. 26, 1949 IN V EN TOR.

Patented Dec. 4, 1 951 FLOATING DRY DOCK Gunnar C. Eng strand, New York,N. Y., assignor, V

by mesne assignments, to Frederic R. Harris, Inc., New York, N. Y., acorporation of New York I Application November 26, 1949, Serial No.129,680

My invention relates to an improvement in floating drydocks, and it hasfor its object to provide a floating drydock of extreme economy instructure as well as in upkeep. While floating dock investigations,discussions and design for many years have centered on the constructionof a dock suitable for self-docking without sacrificing the advantagesof the one-piece trough clock, that is a dock which does not haveseparable sections that can be detached for repair and cleaning suchefforts have failed to produce a onepiece trough dock of conventionaldimensions that is innately self-docking. To this end, my inventionrelates to a floating dry deck that is formed as a single trough orone-piece dock and is provided with internal means as well as externalspecial mooring arrangements that permit the entire bottom to be exposedby careening the docks, so that scraping and painting thereof as well asbottom repairs may be undertaken at suitable times without any specialand costly preparations, and frequent bottom inspections can be maderoutine, so that bottom pitting and rusting will get no chance todevelop.

In the drawing, Figure 1 represents my preferred structure in its piermoorings and submerged to maximum draft. Figure 2 shows the structure inself-docking position in its pier moorings. Figure 3 is a detail drawingof the mooring devices on an enlarged scale. characters denotecorresponding parts, i repre sents my preferred clock which comprises apontoon hull and hollow side or wing walls that extend along the hulland enclose the side chambers 2 and 2, which are adapted to containwater, a pontoon hull and hollow side or wing" walls that extend alongthe hull and enclose the adjacent buoyancy chambers 4 and 4', that areadapted to carry the docks own weight, and the central pumpingcompartments -3 and 3', all of which are arranged symmetrically aroundthe center bulkhead 6. Pipes H and I1 provide communication between theside chambers 2 and 2 and the central pontoon chambers.

The combination of the central bulkhead 6 which separates thecompartments or chambers 3 and 3 from each other, and the buoyancychambers located at a distance from bulkhead 6 and also located at adistance from the sides of the pontoon hull, enables the operation ofthe dock to be so controlled that the effects of the upsetting movementsof the free water inside the hull when the dock is raised are virtuallyeliminated. Therefore the maximum water pressure to which the structureis subjected is greatly reduced.

In the drawing Where like i 2 Claims. (Cl. 114-45) 2 I This fact allowsa great saving in the width of the drydock and the weight. The wings inparticular can be narrow in thickness; and with the dock having smallerwidth and reduced weight much steel or other material used in theconstruction of the dock can be saved.

The sides of the dock are provided with identical mooring spuds 5 and 5,which are so arranged that the dock may be swung around for theself-docking of the opposite side. The pier l is shown provided withrelatively short mooring spuds 9 to allow for tidal as well as operativelevel variations. A double mooring jaw 8 comprises the jaw l0, which isadapted to slide on a dock spud 5" and this jaw is hinged to the jaw II,which, in turn, is adapted to slide on a spud 9 attached to a pier orother fixed support. When the dock is used for regular ship service, thejaw II is locked to the pier spud 9 by a pair of looking pins l2, whichare adapted for insertion into the holes l3, with which the spuds areprovided, and the pivot pin M allows the free listing of the dock inregular ship service as well as in selfdocking operations. Of coursethere will be several spuds 5 and 5 at diiierent points along the lengthof the sides of the dock and several spuds 9 on the pier I, and eachspud on the side of the dock will be connected to an adjacent spud onthe pier by a separate mooring jaw 8.

I prefer to make the buoyant chambers i4' larger than the requirementsfor the support of the dock weight, and I, therefore, have to pump waterinto the side chambers when the empty dock is being submerged. Themaximum draft is r reached when the freeboard space at the top of theside chambers is filled with water. Theshown arrangement results in aVery stable dock structure at the critical point, when the ship justemerges from the water and the balancing is performed solely by the sidechambers. The only free water surfaces inside the dock at this momentare defined by the innermost bulkheads 6aof the buoyancy chambers, andthe center bulkhead, and relatively narrow wings will suifice, whichmeans a narrower dock structure with a corresponding saving in material.Spaces 4 i' contain the pump gear.

In general shape the dock resembles a large trough with bottom uprightsides and two opposite open ends. Ihe wing or side walls enclosing thechambers 2 and 2 include outer or outboard walls l8 and inner or inboardwalls is rising above the level of the deck 28 of the pontoon hullindicated at 2| between them. Both walls l8 and I9 extend down to thebottom of the dock and the lower parts Ilia of the inboard walls l9constitute watertight bulkheads separating the chambers 2 and 2 from thebuoyancy chambers 4 and 4' respectively. The bottom part 22 of the dockis horizontal and parallel to the deck 29, and the flood chambers 3 and3' are thus contained between the ends of the pontoon hull, the deck 20and the middle part 22 of the bottom; the long central bulkhead 6dividing the chambers 3 and 3 from each other. Under the chambers 2 and4, and 2 and 4', the bottom slopes upward from each side of the mid partof section 22-, as indicated at 23. The side walls are of course closedat the tops 24, over the chambers g and 2' and at the ends, and when thedock is at margimum draft or fully submerged, the freeboard parts of theside walls which remain above the water level are indicated at 25. Thebottom can be parallel to the deck 28 over its full width if desired.

In Figure 2, I have shown diagrammatically the load conditions atself-docking with the dock tilted in its moorings for bottom repair. Thejaw l l is locked to the pier stud 9 by means of the pins l2 and thatthe dock is free to move up and down with tidal variations. In regularservice the jaws II] can slide on the spuds ,or rails 5 while themooring devices are locked to the spuds 9. When the dock is in a tiltedposition the jaws II] are preferably locked to the spuds or rails bypins 12 to prevent movement of the dock; the tops of the spuds 5 havingholes into which the pins are inserted. The dock weight is representedby the force W and W and W" are the respective weights of the excesswater masses inside the side chamber 2' and the pontoon chamber 3'. Thethree weights are supported by the buoyancy force of chamber 4 togetherwith that part of chamber 3 that lies between the. outside water lineand the buoyancy chamber, which force isdenoted by B in the drawing.

The existance of the excess water it in chamher 3' and a vacant space atthe top of the side chamber 2' indicates that the dock may be tiltedstill more than shown in the drawing. Which is a true scale drawing ofmy preferred floating dry dock.

A dock of this design can easily be tilted so that more than half of itsbottom is exposed regardless of the cross-sectional shape of the hull. Imight make the hull rectangular in cross-section and tilt it with thesame ease and certainty.

It is apparent that I have provided a dock that constitutes animprovement on the prior art, and I wish to be understood to claim such'modiiications that properly fall within the scODe of my inyention andthe terms of the following claims:

1. A floating drydock structure comprising a pontoon hull, said hullhaving a centrally longitudinally-extending bulkhead, alongitudinallyextending bulkhead disposed on each side of said firstbulkhead and spaced from the sides of the hull, said bulkheads forming apair of watertight flooding chambers adjacent said central bulkhead,wing chambers adjacent each side of said pontoon hull, each of said wingchambers inciuding spaced inner and outer side walls extending from thebottom of the pontoon hull and above the" top thereof, the inner wallsof said wing chambers cooperating with said longitudinal bulkheads toform hiio'y'ancy chambers of such size 59. as to support'the drydockwhen said Wing chambers and said flooding chambers are filled with waterand means attached to one of said outer side walls and adapted tocooperate with a support for holding said drydock in tilted positionrelative to the support, said wing chambers and said flooding chambersbeing so proportioned that when'one' wing chamber and both floodingchambers are substantially empty and the other of' saidwing chambers issubstantially filled with water, there produced an asymmetrical load ingwithin the said structure, which by reason or the displacement of thebuoyancy off the structure effects a tiltingthereof about said means tothere by'expose more'than one half of the bottom of the pontoonhull'above'the surface of the water of floatation." J

2. The floating drydock structure as defined in claim 1, wherein saidmeans comprises a jaw adapted to be secured to the support, and a jawslidably connected to said wing wall and pivotally united tothe'firstnamed'jaw.

GUNNAR C. ENGSTRAND.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 01,554 Clark" Mar. 29, 1398755,354 Dieckhoff Mar. 29', 1904. 853,323 Wiking May .14, 1907 1,267,956Baeck' May 28, 1918 1',6 }03 McCl re May 2 1928 FOREIGN PATENTS NumberCountry Date 381,65 Austria Aug. 25 1909 343,634 France Aug; 11, 1904

